refactor(registrar): simplify registration manager dedupe

[jackchuma]

What changed? Why?

RegistrationManager no longer owns a process-local in-flight signer set; it now focuses on the single-signer registration path: checking whether the signer still needs registration, generating or recovering the proof, and handing the result to ProofHandler.

This also removes the old in-flight guard export and updates the registrar driver glue that constructed RegistrationManager.

Notes to reviewers

Task-level deduplication remains owned by the registrar driver pending task tracking.

How has it been tested?

• cargo fmt
• cargo test -p base-proof-tee-registrar

[cb-heimdall]

✅ Heimdall Review Status

Requirement	Status	More Info
Reviews	✅ 1/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1

[github-actions]

Review Summary

No issues found. This is a clean refactor that correctly removes redundant deduplication from RegistrationManager.

What was removed:

• in_flight_registrations: Arc<Mutex<HashSet<Address>>> from RegistrationDriver and the corresponding &Arc<Mutex<HashSet<Address>>> borrow in RegistrationManager
• InFlightRegistrationGuard RAII type and its try_acquire/Drop impl
• prepare_registration_attempt (replaced by signer_needs_registration which returns bool instead of Option<Guard>)
• invoke_proof_handler (inlined at the single call site)
• Two tests that specifically exercised the mutex-based deduplication

Why it's safe: The removed mutex was defence-in-depth. The driver's reconcile_proof_tasks already provides single-threaded deduplication via its local in_flight: HashSet<Address> built each cycle, and apply_join_outcome's task-id guard prevents stale joins from evicting fresh pending entries. Since reconcile_proof_tasks is the sole spawn path and runs synchronously within the run loop, no concurrent duplicate can slip through.

The updated doc comments accurately describe the new deduplication invariants.

[github-actions]

✅ base-std fork tests: all 616 passed

base/base is fully in sync with the base-std spec.

Dependency	Ref	Commit
base-std	main	e25553dc
base-anvil	0092692587d8d064dd2c6923ce26a682c58f3694	00926925

[mw2000]

🧹 clean